With the development of wireless communication technology, various modes, such as GSM (Global System of Mobile Communication, global system of mobile communication), UMTS (Universal Mobile Telecommunications System, universal mobile telecommunications system), LTE (Long Term Evolution, long term evolution), LTE-A (Long Term Evolution-Advanced, long term evolution-advanced) and the like, are mutually merged in their respective development processes, and on an access network side, particularly, various radio modes are evolving towards a direction of having unified RRM (Radio Resource Management, radio resource management).
When multiple radio access technology (Multiple Radio Access Technology, Multi-RAT) supports a user equipment (User Equipment, UE) in performing data transmissions in multiple modes at a same time, both throughput of a user and user experience may be improved. For example, in a WiFi offloading technology, WLAN (Wireless Local Area Network, wireless local area network) may be used as an access network of a 3G (The third Generation, the third generation) core network, whereby UE may perform data transmissions via a WiFi air interface and a 3G air interface simultaneously. Under a circumstance that WiFi offloading is realized in a tight coupling manner, a user equipment and a packet network may interchange data through a 3G core network, a 3G access network and a 3G air interface provided by the 3G access network, or through a 3G core network, a WLAN access network and a WiFi air interface provided by the WLAN access network, or through a 3G air interface and a WiFi air interface at a same time. Although the WLAN and the 3G network are taken as an example for illustrating the tight coupling manner in the aforementioned example, persons skilled in the art may think of the tight coupling manner also present in other network architecture, such as WLAN and LTE network.
In an existing Multi-RAT scenario, if data transmission is provided for a UE via a plurality of air interfaces at a same time, a service currently carried by an air interface is interrupted when the air interface is unavailable, leading to a failure of data transmission on the air interface. In the absence of a mechanism for processing the service carried by the unavailable air interface under the Multi-RAT condition, data transmission of the UE is affected.